When does a skydiver achieve terminal velocity?

Using 15 percent as machine energy efficiency, what is the actual work output if the total work input is 7500 kilojoules?

g100num [7]

Answer:

The actual work output is 1,125 kilojoules.

Explanation:

Energy efficiency is defined as the efficient use of energy. An appliance, process, or facility is energy efficient when it consumes less than the average amount of energy to perform an activity. Then, energy efficiency is the ratio between the amount of energy used in an activity and the amount expected to be carried out.

Efficiency is calculated as:

efficiency = output / input

Where output is the amount of mechanical work (in watts) or energy consumed by the process (in joules), and input (input) is the amount of work or energy that is used as input to carry out the process.

In this case:

Efficiency always has a value between 0 and 1. In this case, efficiency=0.15
output=?
input= 7500 kilojoules

Replacing:

0.15=output/7500 kilojoules

Solving:

Output=0.15* 7500 kilojoules

output=1,125 kilojoules

<u><em>The actual work output is 1,125 kilojoules.</em></u>

7 0

3 years ago

A horizontal uniform bar of mass 2.7 kg and length 3.0 m is hung horizontally on two vertical strings. String 1 is attached to t

Jlenok [28]

Answer:

14.36 N

Explanation:

$T_{1}$ = Tension in string 1

$T_{2}$ = Tension in string 2

$m_b$ = mass of the bar = 2.7 kg

$W_b$ = weight of the bar

weight of the bar is given as

$W_b = m_{b} g = (2.7) (9.8) = 26.46$ N

$m_m$ = mass of the bar = 1.35 kg

$W_m$ = weight of the monkey

weight of the monkey is given as

$W_m = m_{m} g = (1.35) (9.8) = 13.23$ N

Using equilibrium of torque about left end

$W_{m} (AB) + W_{b} (AB) = T_{2} (AC)\\W_{m} (AB) + W_{b} (AB) = T_{2} (AD - CD)\\(13.23) (1.5) + (26.46)(1.5) = T_{2} (3 - 0.65)\\\\T_{2} = 25.33$ N

Using equilibrium of force in vertical direction

$T_{1} + T_{2} = W_{b} + W_{m}\\T_{1} + 25.33 = 26.46 + 13.23\\T_{1} = 14.36$ N

7 0

3 years ago

What length of a certain metal wire of diameter 0.15 mm is needed for the wire to have a resistance of 15 ω? the resistivity of

Murljashka [212]

The resistance of the cylindrical wire is $R=\frac{\rho l}{A}$ .

Here $R$ is the resistance, $l$ is the length of the wire and $A$ is the area of cross section. Since the wire is cylindrical $A=\frac{\pi d^2}{4}$ . Rearranging the above equation,

$A=\frac{\rho l}{R}\\ \frac{\pi d^2}{4}=\frac{\rho l}{R}\\ l=\frac{\pi d^2 R}{4 \rho}$

Here $d=0.15, R=15, \rho=1.68(10^{-8})$ .

Substituting numerical values,

$l=\frac{\pi 0.15^2(10^{-6}) (15)}{4 (1.68)(10^{-8})} \\ l=15.78$

The length of the wire is $15.78 \;\;m$

5 0

4 years ago

Which of these is a measure of how much force is applied to an object from gas particle bouncing into it?

IrinaK [193]

Answer:

Pressure

Explanation:

The measure of how much force is applied to an object from gas particle bouncing into it is called pressure.

Pressure is defined as the force per unit area on a body.

Mathematically;

Pressure = $\frac{Force}{Area}$

The pressure of a gas is the combined force with which gas molecules bombard a unit area of the wall of the container. It is the sum of all tiny pushes on the wall of the container.

Various units of pressure are atm, mmHg, torr, pascal e.t.c

4 0

3 years ago

In the circuit diagram, what does the symbol made of two Long lines and two short lines with a positive and a negative sign at e

Licemer1 [7]

That symbol represents a source of DC, usually a battery.

The zig-zag line represents a resistor, and the two little circles
connected by a short line represent a switch in the closed position.,

8 0

3 years ago